The prior art provides various portable saws for cutting grooves into surfaces such as concrete and asphalt. Examples of such prior art saws may be found in Zuzelo U.S. Pat. No. 3,747,981 and Shatwell, et al. U.S. Pat. No. 3,663,060. Unfortunately, such prior art saws display some disadvantages. More particularly, prior art saws such as that disclosed by Shatwell, et al. require that the power source or engine which is used to drive the rotary saw blade be vertically adjusted or moved relative to the housing or frame of the saw in order to effectuate a change in the cutting depth of the saw blade. Also, saws such as that disclosed by Shatwell, et al. utilize lever assemblies which can be quite difficult and awkward for a user to operate. More particularly, some of the lever assemblies require the user to remove one or more hands from the handgrips of the saw in order to operate the lever assembly.
Prior art saws, such as that disclosed by Zuzelo, also display some disadvantages for they employ handwheels which are mounted upon threaded rods for adjusting the vertical height of the saw blade. In order to effectuate a significant vertical adjustment of the saw blade, a considerable amount of the user's time can be required to rotate the handwheel. Additionally, such saws generally require the user to remove one or more hands from the handgrips of the saw in order to rotate the handwheel.
Because many of the prior art saws are difficult to height adjust, many times a user, upon completion of a cut, will merely tilt the saw back on its rear wheels and move the saw about on its rear wheels instead of using the height adjustment mechanism to raise and lower the blade. While tilting the saw back, the user many times tilts the saw back much more than that which is necessary to clear the blade from the cutting surface. When an internal combustion engine is employed to drive the saw blade, this excessive tilting resulting in the substantial displacement of the oil within the engine. The substantial displacement of the oil leads to the improper internal oiling of the engine parts and thus a shortened service life for the engine.